1. Field of the Invention
The invention concerns a safety relay with at least one electromagnetic drive, which comprises a coil with a core/yoke that can be connected to a control current and a movable armature. The relay also comprises a comb that can be moved by means of the armature and several contacts arranged on an electrically insulating carrier part. The drive is arranged on one side of a separating wall; comb and contacts are on the other side of the separating wall. The invention particularly concerns a twin relay of the aforementioned type. The twin relay is a safety relay with two electromagnetic drives. These drives are arranged on one side of a separating wall. Two combs and two rows of contacts are arranged correspondingly on the other side of the separating wall.
2. Brief Description of Art
A twin relay, which is approximately 15 mm high, 65 mm wide, and 76 mm long, and the structural height of which is formed by two planes, is described in WO 99/54,905. In one of the planes, for example on the side of the connections, two drive systems (opposite-poled sliding armatures) are accommodated. The contact sets are arranged in the other plane. The contact sets each are formed by two contacts individually driven by one of the drives that are independent of one another, and these contacts are connected internally in series. The contacts are formed by one or two contact springs. If a contact is formed by two contact springs, then the active or the passive contact spring extending over the entire width or length of the relay is clamped in the center in a chamber separating wall, and possesses a contact head on both ends. This contact head cooperates with a contact spring, which has a terminal connection on the outside of the relay. If the individual contact is formed of a single contact spring only, then the latter is forcibly-commutated together with the comb and its contact head cooperates directly with the contact head of the contact spring of the other contact of the contact set. This contact spring of the second contact is in turn forcibly-commutated together with a second comb. The two combs each move in opposite directions. The contact springs extend parallel to a separating wall between the two planes. The prior art document is silent with respect to the position and configuration of the drive with armature and comb.
Nowadays a relay must meet two partially contradictory requirements. These requirements must be considered in the development of new relays in order to be competitive in the marketplace. The first requirement is that relays must be made smaller. On the other hand it is required of the relays that they be durable and reliable. In a safety relay which meets EN (European Standard) 50205, the air paths and leakage paths between control contact and load contact comply with the requirements of standard IEC 61810-5 and IEC 664-1. The contents of these standards are known to the person skilled in the art and are included by reference. Depending on the voltage, the degree of contamination and the field of application, the known distances between conductive components of the different load contacts must be maintained. In addition, the forced commutation of the contacts further serves for purposes of safety.
In accordance with the present invention, a forcibly-commutated relay is a relay in which the contacts are forcibly-commutated with a common movable comb that is connected with the drive and in which at least one working contact and one resting contact are provided. Forcibly commutated here means that each time a contact element abuts a fixed stop, a movable contact spring cooperating with this contact element engages in the comb in such a way that it is forcibly moved together with the movements of the comb. With this constructive measure, it is ascertained that in case a contact is welded, either the welded contact breaks or the comb cannot be moved and thus the other contacts, including the resting contact, also remain in the position given by the welded contact.
Thus, the object of the invention is to provide a safety relay of compact and simple construction, with which reliable, durable operation is assured. Preferably the relay is miniaturized. In addition the relay shall be easy to assemble and optimally adjustable.
The adjustment of the contacts forms an important aspect for assuring safety and durability of a relay. A sufficient adjustment of the contacts is more difficult to obtain the smaller the relay is and the smaller the clearances relative to the force equilibrium of the drive/spring and the 3-dimensional distances are selected. Thus high requirements are to be placed on adjustability in the case of a miniaturized relay.
The adjustability of the safety relay or the twin relay of the present invention is achieved in that the contact springs are arranged between the comb and the separating wall separating the drive side from the contact side.
The safety relay has at least one electromagnetic drive, which comprises at least one coil with a core/yoke that can be connected to a control current and a movable armature. This drive is arranged on one side of a separating wall which extends parallel to the core. A comb that can be moved parallel to the separating wall by means of the armature and a row of several contacts which are arranged on an electrically insulating carrier part are located on the other side of the separating wall. The contacts are comprised of at least two contact elements and can be actuated by the drive. At least one of the contact elements is connected with a current connection element, for example a pin on the outer side of the relay. Likewise, at least one of the contact elements is formed by an elongated contact spring. The longitudinal axis of this contact spring is arranged transverse to the direction of motion of the comb and extends advantageously parallel to the plane of the separating wall. The contact spring is forcibly-commutated by the comb. The contact spring with its spring foot on one end is accomodated firmly in the carrier part. On its opposite movable end it is provided with a contact head. For an optimal construction of the relay, the contact springs are arranged between the comb and the separating wall. With this construction, the length of the armature can take up the entire height of the relay, and a relatively large comb path is achieved with relatively small structural height.
Advantageously, a removable outer wall of the contact chamber on the comb side of the contact spring that lies opposite the separating wall for closure of the relay. This allows one to insert the comb into the carrier part after introducing the contact elements, and holding it in its catching position by means of the outer wall of the chamber. If the contacts can be arranged in a functional manner in the opened relay, it is assured by this arrangement that the contacts can be optimally adjusted. When adjusting the contacts, the contacts are firmly secured in the carrier part, are not in engagement with the comb, and are freely accessible from the open outer wall of the chamber. In order to control the adjustment, the comb can be temporarily inserted with the relay still open. Only after the correct adjustment has been controlled, the comb is definitively inserted and the outer wall of the chamber is put in place, and thus the relay is sealed.
Preferably, the individual contacts are separated from one another by chamber walls. Advantageously, the comb is formed by a longitudinal bar extending through cutouts in the chamber walls. This longitudinal bar can be arranged in the vicinity of the contact springs and is engaged with the contact springs by means of suitable formations on the bar. Due to the drive arrangement, the longitudinal bar is advantageously arranged in the center between the outer edges of the relay or relay part. Shields are provided on at least three sides of the longitudinal bar, which are arranged approximately parallel to the chamber walls and extend beyond the sides of the longitudinal bar, in order to elongate the air and leakage paths between contact elements of adjacent contacts in the region of the through-passages of the bar. A labyrinthine extension of the air and leakage paths is achieved by overlapping the chamber walls with the shields.
Preferably, the engagement portion of the contact spring on the comb has a distance to the bar axis of the comb, parallel to the longitudinal axis of the spring. As a result of such distance, the longitudinal bar of the comb can be arranged centrally, while the contact spring engages the comb at a selectable distance to the spring foot and the contact head.
Preferably, the dimensions of the drive and the contacts are selected to correspond with one another, by providing that the totality of the chambers housing the contacts actuated with a drive leave approximately the same dimensions in two directions as the coil assigned to the contacts. Thus the chambers and the coil having practically the same extensions, the available space is optimally utilized. Resulting from its considerable length the coil may be selected as a relatively high-ohm coil, despite its reduced height.
The chamber walls for separating adjacent chambers may be formed on the carrier part or protruding from the outer wall of the chamber. Advantageously, they are formed on both parts. Thus, air and leakage paths are lengthened by an overlapping of the chamber walls.
Preferably, at least one portion of the contacts is provided with two independent terminal elements. Contacts having only one terminal element extending to the outside are appropriate for twin relays. These contacts are connected in series with a second contact, which is actuated by a second coil. In the ordinary single relay, all of the contacts have two terminal elements, or three in the case of double-throw contacts, which extend to the outside of the relay. Such contacts are particularly suitable as control contacts, even in twin relays.
In a further advantageous embodiment of the invention, the contact springs between their contact head and the spring foot each have a projection with a comb attachment protruding away from the separating wall towards the comb side. The contact spring is forcibly engaged with the comb by the comb attachment. A lateral protrusion on the contact spring allows to insert the comb between the head end and the foot end of the contact spring next to the projection. The contact spring may be notched in the region adjoining the protrusion for guiding the comb therethrough. Thus, the comb may be shaped mirror symmetrically with respect to a plane through the bar axis extending perpendicularly to the separating wall. The projection then engages in one of the two formations provided for engagement. This permits the use of a uniform comb even in the case of a twin relay of the type described below.
Advantageously, the contact spring is engaged with the comb at a comb attachment, which is located at a distance from the mechanical longitudinal axis of the spring. The distance to the mechanical longitudinal axis causes a twisting of the contact spring when the contact is connected, which acts favorably on the life-span of the contact head and thus on the durability of the relay.
Preferably, the contact head is attached to the spring by its center at a preselected distance beneath the mechanical longitudinal axis of the contact spring. This also causes a twisting of the spring and a favorable effect on the contact head when the contact is connected. The preselected distance is preferably smaller than the distance between the comb attachment and the longitudinal axis of the spring.
In the direction of the longitudinal axis of the spring, the distance of the comb attachment from the spring foot is preferably about double its distance from the center of the contact head, in order to achieve good guidance and sufficient length of movement of the contact head.
Such a relay with six contacts can be made very small while fulfilling the requirements of the standards indicated initially. The terminal ports are located on the side of the contacts and the drive is arranged above the contacts and extends over practically the entire length of the relay. The relatively large space available for the winding allows an efficient drive with small coil losses. On the side of the armature, on the relay end, terminal ports are provided for the coils.
The advantages stated above also apply to a safety relay with two electromagnetic drives, for example a twin relay. Twin relays have a coil with a core that can be connected to a control current and a movable armature for each drive. The coils are preferably aligned the same way, so that the armatures are located on the same side. The drives are arranged on one side of a separating wall which extends parallel to the cores, while each armature extends across the separating wall. Two combs movable parallel to the separating wall, and two rows of several contacts which are arranged on an electrically insulating carrier part, are arranged next to one another on the other side of the separating wall. The contact springs are arranged with their longitudinal axis parallel to the separating wall. The combs are driven independently of one another, each by one of the armatures. At least two of the contacts actuated thereby independently of one another are joined via a common contact element.
According to the invention, the contact springs are arranged between the comb and the separating wall. The contacts, which have only one terminal element and are connected with a second such contact by means of a common contact element, are preferably arranged on the end of the comb opposite the armature. In this way, preferably a center region arranged underneath the relay and adjacent to at least one edge of the relay, is free of terminal elements. This permits to arrange contact lines to the terminal elements of the contacts having two terminal elements, the contact lines extending in the direction of motion of the comb underneath the relay.
Advantageously, in the case of the contact springs of the contacts which are joined with one another by a common contact element and forcibly commuted by the combs, the spring feet are arranged at ends turned away from one another. Appropriately, the contact heads are arranged between the contact feet of the two contact springs driven independently and connected to a switching unit at ends of the contact springs which are turned toward one another. This arrangement has the advantage that the movable contact springs have the largest possible length and the stationery common contact element can be formed as small as possible. A twin relay of the above-described construction has twice the area of the single relay.